A boiling water reactor (BWR) typically includes a reactor pressure vessel (RPV) and a spent fuel pool connected by a channel. In a known BWR, the RPV has a generally cylindrical shape and is closed at both ends, e.g., by a bottom head and a removable top head. A top guide is spaced above a core plate within the RPV, and many other components, e.g., steam dryers and fuel bundles, also are located in the RPV. The fuel bundles include first and second ends and are positioned between the top guide and the core plate.
Loading and removing fuel bundles is performed manually using a refueling mast, a hoist, and winch cables. More specifically, the RPV top head is removed, and other components, such as steam dryers, also are removed to enable access to the fuel bundles. An operator stands on a platform positioned over the RPV and using the main hoist and cables, raises and lowers the refueling mast, which may extend more than thirty (30) feet below the platform into the RPV.
One known refueling mast includes several telescopic sections, and is extended into the RPV until it is adjacent a fuel bundle. A single hook grapple extends through the mast and engages the top of the fuel bundle. The grapple is then retracted so that the fuel bundle is lifted into the mast, and the mast and fuel bundle are lifted above the top guide. Once the mast and fuel bundle clear the top guide, the platform is moved to transfer the fuel bundle to the spent fuel pool.
Due to the inability to move more than one fuel bundle at a time, reloading the RPV can be time consuming. It is desirable, of course, to limit the time required to reload the RPV since the reactor must be shut down during reloads. Reducing the amount of time required to perform such reloading also would facilitate reducing operator radiation exposure.